GB506022A - Improvements in or relating to apparatus for quantitative analysis by means of x-rays - Google Patents

Abstract

506,022. Determining physical qualities of materials. HAMOS, L. VON. Nov. 23, 1937, No. 32203. Convention date, Dec. 21, 1936. [Class 37] [Also in Group XX] Apparatus for quantitative analysis by X-rays comprises an X-ray source, at least one crystal having a concave surface formed by a bent cleavage plane for focusing the X-rays, and two ionization chambers which receive two spectral images from the sample or samples. The sample 1 to be analysed and the sample 2 of known composition are both subjected to X-rays which produce secondary X-rays of wavelength and intensity dependent on the chemical composition of the samples. These secondary X-rays are diffracted by the concave surface of a crystal 4, and the ionization chambers are placed to receive rays having the characteristic wavelengths. The insulated electrodes of the ionization chambers 6, 7 are connected to a voltage source 8 over resistances 9, 10, an instrument 11 determining the difference in the potential gradients. A shutter 12 movable over the sample 2 varies the ionization in its chamber. When the instrument 11 is brought to zero, the scale position 13 of the shutter 12 indicates the amount of the element in the sample 1. In a modification, Fig. 2, a variable condenser 19 and fixed condenser 18 are connected in parallel to the ionization chambers 7, 6, and the capacity of the condenser 19 is varied until the discharge current in each is equal. The capacity of the condenser 19 is then a measure of the quantity of the element in the sample. Glow tubes or relays may be included to indicate equal rates of discharge in the ionization chambers. In a further modification, the image spectra are produced by two different crystals. In Fig. 5, the critical absorption of the X-rays by the sample is determined by passing the S radiation through the sample 27, the spectral images 28, 29 being measured in the ionization chambers 7, 6.